Fireproofed thermoplastic moulding masses

ABSTRACT

Flame-retardant thermoplastic molding compositions comprise 
     A) from 5 to 99% by weight of a thermoplastic polymer, 
     B) from 0.1 to 50% by weight of a phosphazene of the general formula I 
     
         (PN.sub.2-x H.sub.1-y).sub.z                               I 
    
      where the numerical values of x, y and z, independently of one another, are as follows: 
     1&gt;x&gt;0.05 
     1&gt;y&gt;0.05 
     z&gt;1, and 
     C) from 0 to 70% by weight of other additives and processing aids, 
     where the total of the percentages by weight of components A) to C) is 100%.

The invention relates to flame-retardant thermoplastic moldingcompositions, comprising

A) from 5 to 99% by weight of a thermoplastic polymer,

B) from 0.1 to 50% by weight of a phosphazene of the general formula I

    (PN.sub.2-x H.sub.2-y).sub.z                               I

where the numerical values of x, y and z, independently of one another,are as follows:

1>x>0.05

1>y>0.05

z>1, and

C) from 0 to 70% by weight of other additives and processing aids,

where the total of the percentages by weight of components A) to C) is100%.

The invention also relates to the use of the novel molding compositionsfor producing fibers, films and moldings, and also to the resultantmoldings.

One of the disadvantages of halogen-containing flame-retardantthermoplastics is that they are toxicologically hazardous, and to anincreasing extent they are being replaced by halogen-freeflame-retardant thermoplastics.

Important requirements for flame-retardant systems of this type are inparticular a pale intrinsic color, adequate heat resistance duringincorporation into the thermoplastics, and also the retention ofefficacy when fibrous fillers are added ("wicking" effect with glassfibers, adversely affecting flame-retardancy).

Besides red phosphorus, there are four other possible halogen-free flameretardants.

1) Inorganic flame retardants based on hydroxides or on carbonates, inparticular of magnesium. Large amounts of these have to be used to besufficiently effective.

2) Nitrogen-containing flame retardants, such as melamine cyanurate.These mostly exhibit adequate flame retardancy only in unreinforcedthermoplastics.

3) Phosphorus compounds, such as triphenylphosphine oxide as flameretardant. In many thermoplastics, these have an undesirableplasticizing side-effect.

4) Ammonium polyphosphates or melamine phosphate. These do not haveadequate thermal stability above 200° C.

Phosphazenes and their effectiveness as flame-retardants inthermoplastics have been disclosed in U.S. Pat. No. 3,332,905 and in C.W. Allen, Journal of Fire Sciences 11, 1993, p. 320-328.

EP-A 417 839 has disclosed the addition of a phospham of the formula(PN₂ H)_(x) as a flame retardant for thermoplastics. Thermo-gravimetricstudies in EP-A 417 839 have shown that (PN₂ H)_(x) is heat-resistant upto 390° C., but has disadvantages in other flame-retardant properties,since there is no crust formation on ignition and this makes itnecessary to add an antidrip agent to prevent burning drops, and also anadditive to promote carbonization.

It is an object of the present invention to provide a flame retardantfor thermoplastics which gives adequate crust formation andcarbonization on ignition, and does not give burning drops.

We have found that this object is achieved by means of the moldingcompositions defined at the outset. Preferred embodiments are given inthe subclaims.

Surprisingly, the addition of a highly crosslinked phosphazene givesflame-retardant molding compositions which do not give burning drops andhave adequate crust formation and carbonization. This is surprisingbecause highly crosslinked phosphazenes are very thermally stable, i.e.chemically inert, and thus should have poorer effectiveness.

The novel molding compositions comprise, as component A) from 5 to 99%by weight, preferably from 10 to 80% by weight and in particular from 30to 80% by weight of a thermoplastic polymer.

In principle, the advantageous effect in the novel molding compositionsis apparent with thermoplastics of any type. A list of suitablethermoplastics is found, for example, in Kunststoff-Taschenbuch (ed.Saechtling), 1989 edition, in which supply sources are also mentioned.Processes for preparing such thermoplastics or thermosets are known perse to the person skilled in the art. Some preferred plastics types willbe described below in somewhat more detail.

1. Polyoxymethylene homo- or copolymers

Polymers of this type are known per se to the person skilled in the artand are described in the literature.

Very generally, these polymers have at least 50 mol % of recurring --CH₂O-- units in the main polymer chain.

The homopolymers are generally prepared by polymerizing formaldehyde ortrioxane, preferably in the presence of suitable catalysts.

For the purposes of the invention, preference is given topoly-oxymethylene copolymers, in particular those which, besides therecurring --CH₂ O-- units, also have up to 50 mol %, preferably from 0.1to 20 mol % and in particular from 0.3 to 10 mol %, of recurring units##STR1## where R¹ to R⁴, independently of one another, are hydrogen, C₁-C₄ -alkyl or halo-substituted alkyl having from 1 to 4 carbon atoms,and R⁵ is --CH₂ --, --CH₂ O--, C₁ -C₄ -alkyl- or C₁ -C₄-haloalkyl-substituted methylene, or a corresponding oxymethylene group,and n is in the range from 0 to 3. These groups may advantageously beintroduced into the copolymers by ring-opening of cyclic ethers.Preferred cyclic ethers are those of the formula ##STR2## where R¹ to R⁵and n are as defined above. Merely as examples, mention may be made ofethylene oxide, propylene 1,2-oxide, butylene 1,2-oxide, butylene1,3-oxide, 1,3-dioxane, 1,3-dioxolane and 1,3-dioxepan as cyclic ethers,and also linear oligo- or polyformals, such as polydioxolane orpolydioxepan, as comonomers.

Equally suitable polymers are oxymethylene terpolymers, prepared, forexample, by reacting trioxane, one of the cyclic ethers described aboveand a third monomer, preferably a bifunctional compound of the formula##STR3## where Z is a chemical bond, --O--, or --ORO-- (R=C₁ - to C₈-alkylene or C₂ -C₈ -cycloalkylene).

Preferred monomers of this type are ethylene diglycide, diglycidyl etherand diethers from glycidyls and formaldehyde, dioxane or trioxane in amolar ratio of 2:1, and also diethers from 2 mol of glycidyl compoundand 1 mol of an aliphatic diol having from 2 to 8 carbon atoms, such asthe diglycidyl ethers of ethylene glycol, 1,4-butanediol,1,3-butanediol, 1,3-cyclo-butanediol, 1,2-propanediol and1,4-cyclohexanediol, to name only a few examples.

Processes for preparing the homo- and copolymers described above areknown to the person skilled in the art and are described in theliterature, and further details here are therefore unnecessary.

The preferred polyoxymethylene copolymers have melting points of atleast 150° C. and molecular weights (weight average) M_(W) in the rangefrom 5000 to 200,000, preferably from 7000 to 150,000.

End-group-stabilized polyoxymethylene polymers which have C--C bonds attheir chain ends are particularly preferred.

2. Polycarbonates and polyesters

Suitable polycarbonates are known per se. They are obtainable, forexample, by interfacial polycondensation as in the processes of DE-B-1300 266, or by reacting diphenyl carbonate with bisphenols as in theprocess of DE-A-14 95 730. A preferred bisphenol is2,2-di(4-hydroxyphenyl)propane, which is referred to generally, and alsobelow, as bisphenol A.

Instead of bisphenol A it is also possible to use other aromaticdihydroxy compounds, in particular 2,2-di(4-hydroxyphenyl)-pentane,2,6-dihydroxynaphthalene, 4,4'-dihydroxydiphenyl sulfone,4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfite,4,4'-dihydroxydiphenyl methane, 1,1-di(4-hydroxy-phenyl)ethane or4,4-dihydroxydiphenyl and also mixtures of the abovementioned dihydroxycompounds.

Particular preference is given to polycarbonates based on bisphenol A orbisphenol A together with up to 30 mol % of the abovementioned dihydroxycompounds.

The relative viscosity of these polycarbonates is generally in the rangefrom 1.1 to 1.5, in particular from 1.28 to 1.4 (measured at 25° C. in a0.5% strength by weight solution in dichloromethane).

Suitable polyesters are likewise known per se and described in theliterature. In their main chain, they contain an aromatic ring which isderived from an aromatic dicarboxylic acid. The aromatic ring may alsobe substituted, e.g. by halogen, such as chlorine and bromine, or by C₁-C₄ -alkyl, such as methyl, ethyl, isopropyl, n-propyl, n-butyl,isobutyl and/or tert-butyl.

The polyesters may be prepared by reacting aromatic dicarboxylic acids,their esters, or other ester-forming derivatives of the same, withaliphatic dihydroxy compounds, in a manner known per se.

Preferred dicarboxylic acids which may be mentioned arenaphthalenedicarboxylic acid, terephthalic acid and isophthalic acid andmixtures of these. Up to 10 mol % of the aromatic dicarboxylic acids maybe replaced by aliphatic or cycloaliphatic dicarboxylic acids, such asadipic acid, azelaic acid, sebacic acid, dodecanedioic acids andcyclohexanedicarboxylic acids.

Of the aliphatic dihydroxy compounds, preference is given to diolshaving from 2 to 6 carbon atoms, in particular 1,2-ethanediol,1,4-butanediol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol andneopentyl glycol, or mixtures of these.

Particularly preferred polyesters which may be mentioned arepolyalkylene terephthalates derived from alkanediols having from 2 to 6carbon atoms. Of these, particular preference is given to polyethyleneterephthalate, polyethylene naphthalate and polybutylene terephthalate.

The viscosity number of the polyesters is generally in the range from 60to 200 ml/g (measured in a 0.5% strength by weight solution in a 1:1mixture of phenol and o-dichlorobenzene at 25° C.)

3. Polyolefins

Those which may be mentioned here are very generally polyethylene andpolypropylene, and also copolymers based on ethylene or propylene, ifdesired also with higher α-olefins. Corresponding products areobtainable under the tradenames Lupolen® and Novolen® from BASFAktiengesellschaft.

4. Poly(meth)acrylates

Under this heading, mention is made in particular of polymethylmethacrylate (PMMA), and also copolymers based on methyl methacrylatewith up to 40% by weight of other copolymerizable monomers, asobtainable, for example, under the designations Lucryl® from BASFAktiengesellschaft or Plexiglas® from Rohm GmbH.

5. Polyamides

Preference is given very generally to any type of polyamide withaliphatic and partly crystalline, or partially aromatic and alsoamorphous structure, and blends of these. Corresponding products areavailable under the trade name Ultramid® from BASF AG.

6. Vinylaromatic polymers

The molecular weight of these polymers, which are known per se andcommercially available, is generally in the range from 1,500 to2,000,000, preferably in the range from 70,000 to 1,000,000.

Mention may be made here, merely in a representative capacity, ofvinylaromatic polymers made from styrene, chlorostyrene, α-methylstyreneand p-methylstyrene; comonomers, such as (meth)acrylonitrile or(meth)acrylates, may be involved in the structure in subordinateproportions (preferably not more than 20% by weight, in particular notmore than 8% by weight). Particularly preferred vinylaromatic polymersare polystyrene and impact-modified polystyrene. It is, of course, alsopossible to use mixtures of these polymers. Preparation is preferably bythe process described in EP-A-302 485.

Preferred ASA polymers have been built up from a soft or rubber phasemade from a graft polymer of:

A₁ from 50 to 90% by weight of a graft base based on

A₁₁ from 95 to 99.9% by weight of a C₂ -C₁₀ -alkyl acrylate and

A₁₂ from 0.1 to 5% by weight of a bifunctional monomer having twonon-conjugated olefinic double bonds, and

A₂ from 10 to 50% by weight of a graft made from

A₂₁ from 20 to 50% by weight of styrene or of substituted styrenes ofthe general formula depicted, or mixtures of is these, and

A₂₂ from 10 to 80% by weight of acrylonitrile, methacrylonitrile,acrylates or methacrylates or mixtures of these,

in a mixture with a hard matrix based on an SAN copolymer A₃) made from:

A₃₁ from 50 to 90% by weight, preferably from 55 to 90% by weight and inparticular from 65 to 85% by weight of styrene and/or of substitutedstyrenes of the general formula depicted, and

A₃₂ from 10 to 50% by weight, preferably from 10 to 45% by weight and inparticular from 15 to 35% by weight, of acrylonitrile and/ormethacrylonitrile.

Component A₁) is an elastomer which has a glass transition temperatureof below -200° C., in particular below -300° C.

For preparing the elastomer, the main monomers A₁₁) used are acrylateshaving from 2 to 10 carbon atoms, in particular from 4 to 8 carbonatoms. Particularly preferred monomers which may be mentioned here aretert-butyl, isobutyl and n-butyl acrylate, and also 2-ethylhexylacrylate, of which the two last named are particularly preferred.

Besides these acrylates, use is made of from 0.1 to 5% by weight, inparticular from 1 to 4% by weight, based on the total weight A₁₁ +A₁₂,of a polyfunctional monomer having at least two non-conjugated olefinicdouble bonds. Of these, use is preferably made of bifunctionalcompounds, i.e. those having two non-conjugated double bonds. Thosewhich may be mentioned here as examples are divinylbenzene, diallylfumarate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate,tricyclodecenyl acrylate and dihydrodicyclopentadienyl acrylate, ofwhich the two last named are particularly preferred.

Processes for preparing the graft base A₁ are known per se and aredescribed, for example, in DE-B 1 260 135. Corresponding products arealso commercially available.

In some cases, preparation by emulsion polymerization has provenparticularly advantageous.

The precise polymerization conditions, in particular the type, method ofaddition and amount of the emulsifier, are preferably selected so thatthe latex of the acrylate, which is at least to some extent crosslinked,has an average particle size (ponderal median d₅₀) in the range fromabout 200 to 700 nm, in particular from 250 to 600 nm. The latexpreferably has a narrow particle size distribution, meaning that thequotient ##EQU1## is preferably less than 0.5, in particular less than0.35.

The proportion of the graft base A₁ in the graft polymer A₁ +A₂ is from50 to 90% by weight, preferably from 55 to 85% by weight and inparticular from 60 to 80% by weight, based on the total weight of A₁+A₂.

The graft base A₁ has, grafted onto the same, a graft shell A₂,obtainable by copolymerizing

A₂₁ from 20 to 90% by weight, preferably from 30 to 90% by weight and inparticular from 30 to 80% by weight, of styrene or of substitutedstyrenes of the general formula depicted ##STR4## where R is alkylhaving from 1 to 8 carbon atoms, hydrogen or halogen, and R¹ is alkylhaving from 1 to 8 carbon atoms or halogen, and n is 0, 1, 2 or 3, and

A₂₂ from 10 to 80% by weight, preferably from 10 to 70% by weight and inparticular from 20 to 70% by weight, of acrylonitrile,methacrylonitrile, acrylates or methacrylates, or mixtures of these.

Examples of substituted styrenes are α-methylstyrene, p-methylstyrene,p-chlorostyrene and p-chloro-α-methylstyrene, and of these preference isgiven to styrene and α-methylstyrene.

Preferred acrylates or methacrylates are those whose homopolymers or, asappropriate, copolymers with the other monomers of component A₂₂) haveglass transition temperatures above 20° C. However, it is in principlealso possible to use other acrylates, preferably in amounts which givethe entire component A₂ a glass transition temperature T_(g) above 20°C.

Particular preference is given to esters of acrylic or methacrylic acidwith C₁ -C₈ -alcohols and to esters containing epoxy groups, such asglycidyl acrylate and methacrylate. Very particularly preferred exampleswhich may be mentioned are methyl methacrylate, tert-butyl methacrylate,glycidyl methacrylate and n-butyl acrylate. The last named is preferablynot used in excessively high proportions because of its property offorming polymers with very low T_(g).

The graft shell A₂) may be prepared in one step or in more than one,e.g. two or three, steps, without affecting its overall formulation.

The graft shell is preferably prepared in emulsion, as described, forexample, in DE-C 12 60 135, DE-A 32 27 555, DE-A 31 49 357 and DE-A 3414 118.

Depending on the conditions selected, the graft copolymerization gives acertain proportion of free copolymers of styrene and substituted styrenederivatives, respectively, and (meth)acrylonitrile and (meth)acrylates,respectively.

The graft copolymer A₁ +A₂ generally has an average particle size offrom 100 to 1000 nm, in particular from 200 to 700 nm, (d₅₀ ponderalmedian). The conditions for preparing the elastomer A₁) and for thegrafting are therefore preferably selected in such a way as to giveparticle sizes in this range. Measures for this purpose are known andare described, for example, in DE-C 1 260 135 and DE-A 28 26 925, andalso in Journal of Applied Polymer Science, Vol. 9 (1965), p. 2929 to2938. The enlargement of the elastomer latex particles may be broughtabout, for example, by agglomeration.

For the purposes of this invention, the free, ungrafted homo- andcopolymers produced during the graft copolymerization to preparecomponent A₂) are also counted with the graft polymer A₁ +A₂).

Some preferred graft polymers may be cited below:

1: 60% by weight of graft base A₁ made from

A₁₁ 98% by weight of n-butyl acrylate and

A₁₂ 2% by weight of dihydrodicyclopentadienyl acrylate and

40% by weight of graft shell A₂ made from

A₂₁ 75% by weight of styrene and

A₂₂ 25% by weight of acrylonitrile

2: Graft base as in 1 with 5% by weight of a first graft shell made fromstyrene and

35% by weight of a second graft made from

A₂₁ 75% by weight of styrene and

A₂₂ 25% by weight of acrylonitrile

3: Graft base as in 1 with 13% by weight of a first graft made fromstyrene and 27% by weight of a second graft made from styrene andacrylonitrile in a weight ratio of 3:1

The products obtained as component A₃) may, for example, be prepared bythe process described in DE-B 10 01 001 and DE-B 10 03 436. Copolymersof this type are also commercially available. The weight averagemolecular weight determined by light scattering is preferably in therange from 50,000 to 500,000, in particular from 100,000 to 250,000.

The weight ratio of (A₁ +A₂):A₃ is in the range from 1:2.5 to 2.5:1,preferably from 1:2 to 2:1 and in particular from 1:1.5 to 1.5:1.

SAN polymers which are suitable as component A) have been describedabove (see A₃₁ and A₃₂).

The viscosity number of the SAN polymers, measured in accordance withDIN 53 727 in 0.5% strength by weight solution in dimethylformamide at23° C. is generally in the range from 40 to 100 ml/g, preferably from 50to 80 ml/g.

ABS polymers as polymer (A) in the novel polymer mixtures having morethan one phase have the same structure as described above for ASApolymers. Instead of the acrylate rubber A₁) of the graft base in theASA polymer use is usually made of conjugated dienes, preferably givingthe following formulation for the graft base A₄ :

A₄₁ from 70 to 100% by weight of a conjugated diene and

A₄₂ from 0 to 30% by weight of a bifunctional monomer having twonon-conjugated olefinic double bonds

Graft A₂ and the hard matrix of the SAN copolymer A₃) remain unchangedin the formulation. Products of this type are commercially available.Preparation processes are known to the person skilled in the art, and itis therefore not necessary to give further information on this topic.

The weight ratio of (A₄ +A₂):A₃ is in the range from 3:1 to 1:3,preferably from 2:1 to 1:2.

Particularly preferred formulations of the novel molding compositionscomprise:

A₁) from 10 to 80% by weight of a polybutylene terephthalate,

A₂) from 0 to 40% by weight of a polyethylene terephthalate,

A₃) from 1 to 40% by weight of an ASA or ABS polymer or mixtures ofthese,

B) from 1 to 35% by weight of a phosphazene as claimed in claim 1, and

C) from 0 to 40% by weight of a fibrous or particulate filler ormixtures of these

Products of this type are obtainable under the trademark Ultradur® S(previously Ultrablend® S) from BASF Aktiengesellschaft.

Other preferred formulations comprise

A₁) from 10 to 80% by weight of a polycarbonate,

A₂) from 0 to 40% by weight of a polyester, preferably polybutyleneterephthalate,

A₃) from 1 to 40% by weight of an ASA or ABS polymer or mixtures ofthese,

B) from 1 to 35% by weight of a phosphazene as claimed in claim 1, and

C) from 0 to 40% by weight of a fibrous or particulate filler ormixtures of these.

Products of this type are obtainable under the trademark Terblend® fromBASF AG.

7. Polyarylene ethers

For the purposes of the present invention, polyarylene ethers arepreferably either polyarylene ethers per se, polyarylene ether sulfides,polyarylene ether sulfones or polyarylene ether ketones. The arylenegroups of these may be identical or different and, independently of oneanother, be aromatic radicals having from 6 to 18 carbon atoms. Examplesof suitable arylene radicals are phenylene, biphenylene, terphenylene,1,5-naphthylene, 1,6-naphthylene, 1,5-anthrylene, 9,10-anthrylene and2,6-anthrylene. Of these, preference is given to 1,4-phenylene and4,4'-biphenylene. These aromatic radicals are preferably unsubstituted,but they may carry one or more substituents. Examples of suitablesubstituents are alkyl, arylalkyl, aryl, nitro, cyano and alkoxy, andalso heteroaromatics, such as pyridine, and halogen. Preferredsubstituents include alkyl having up to 10 carbon atoms, such as methyl,ethyl, isopropyl, n-hexyl, isohexyl, C₁ -C₁₀ -alkoxy, such as methoxy,ethoxy, n-propoxy, n-butoxy, aryl having up to 20 carbon atoms, such asphenyl or naphthyl, and also fluorine and chlorine. Besides --O--, thesemay be linked, for example, via --S--, --SO--, --SO₂ --, --CO--,--N=N--, --COO--, alkylene or a chemical bond. The arylene groups in thepolyarylene ethers may also be linked with one another via differentgroups.

Preferred polyarylene ethers include those having recurring units of thegeneral formula depicted ##STR5##

It is also possible to use their ring-substituted derivatives. Preferredsubstituents are C₁ -C₆ -alkyl, such as methyl, ethyl or tert-butyl, C₁-C₆ -alkoxy, such as methoxy or ethoxy, aryl, in particular phenyl,chlorine or fluorine. The variable X may be --SO₂ --, --SO--, --S--,--O--, CO, --N=N--, --RC=CR^(a) --, --CR^(b) R^(c) -- or a chemicalbond. The variable Z may be --SO₂ --, --SO--, --CO--, --O--, --N=N-- or--RC=CR^(a). Each of R and R^(a) here is hydrogen, C₁ -C₆ -alkyl, e.g.methyl, n-propyl or n-hexyl, C₁ -C₆ -alkoxy, including methoxy, ethoxyand butoxy, or aryl, in particular phenyl. Each of R^(b) and R^(c) maybe hydrogen or C₁ -C₆ -alkyl, in particular methyl. However, they mayalso be linked with one another to give a C₄ -C₁₀ -cyclo-alkyl ring,preferably a cyclopentyl or cyclohexyl ring, which may in turn besubstituted with one or more alkyl groups, preferably methyl. Inaddition, R^(b) and R^(c) may also be C_(l) -C₆ -alkoxy, e.g. methoxy orethoxy, or aryl, particularly phenyl. Each of the abovementioned groupsmay in turn be substituted with chlorine or fluorine.

The polyarylene ethers may also be copolymers or block copolymers,comprising polyarylene ether segments and segments of otherthermoplastic polymers, such as polyamides, polyesters, aromaticpolycarbonates, polyestercarbonates, polysiloxanes, polyimides orpolyetherimides. The molecular weights of the blocks or of the graftbranches in the copolymers is generally in the range from 1000 to 30,000g/mol. The blocks of different structure may be arranged alternately orrandomly. The proportion by weight of the polyarylene ether segments inthe copolymers or block copolymers is generally at least 3% by weight,preferably at lest 10% by weight. The proportion by weight of thepolyarylene ether sulfones or polyarylene ether ketones may be up to 97%by weight. It is preferable to use copolymers or block copolymers with aproportion by weight of polyarylene ether segments of up to 90%.Particular preference is given to copolymers or block copolymers withfrom 20 to 80% by weight of polyarylene ether segments.

The polyarylene ethers generally have average molecular weights M_(n)(number average) in the range from 10,000 to 60,000 g/mol and viscositynumbers from 30 to 150 ml/g. Depending on the solubility of thepolyarylene ethers, the viscosity numbers are measured either in 1%strength by weight N-methylpyrrolidone solution, in mixtures of phenoland o-dichlorobenzene, or in 96% strength sulfuric acid, in each case at20 or 25° C.

The polyarylene ethers (A) are known per se or may be prepared bymethods known per se.

Polyphenylene ethers, for example, may therefore be prepared byoxidative coupling of phenols. Polyarylene ether sulfones or polyaryleneether ketones are prepared, for example, by condensing aromaticbishalogen compounds and the alkali metal double salts of aromaticbisphenols. They may also be prepared, for example, by autocondensationof alkali metal salts of aromatic halophenols in the presence of acatalyst.

Preferred process conditions for synthesizing polyarylene ether sulfonesor polyarylene ether ketones are described, for example, in EP-A-113 112and 135 130.

The preferred polyarylene ethers generally have a melting point of,respectively, at least 320° C. (polyarylene ether sulfones) and at least370° C. (polyarylene ether ketones).

According to the invention, the molding compositions may comprise, ascomponent A), polyarylene ether sulfones or polyarylene ether ketones,in both cases obtainable by reacting a polyarylene ether sulfone orpolyarylene ether ketone A₁) with a reactive compound. The reactivecompounds contain, besides a C--C double or triple bond, one or morecarbonyl, carboxylic acid, carboxylate, anhydride, imide, carboxylicester, amino, hydroxyl, epoxy, oxazoline, urethane, urea, lactam orhalobenzyl group(s).

Examples of typical suitable compounds are maleic acid, methyl-maleicacid, itaconic acid, tetrahydrophthalic acid, the anhydrides and imidesthereof, fumaric acid, the mono- and diesters of these acids, e.g. of C₁-C₁₈ -alkanols, the mono- or diamides of these acids, such asN-phenylmaleimide and maleic hydrazide.

Preference is given to the use of modified polyarylene ether sulfones orpolyarylene ether ketones which in both cases have been obtained byreacting from 80 to 99.9% by weight, in particular from 90 to 99% byweight, of the unmodified polyarylene ether sulfones or polyaryleneether ketones with from 0.1 to 20% by weight, in particular from 1 to10% by weight, of the reactive compound.

The free-radical initiators used may generally be the compoundsdescribed in the technical literature (e.g. J. K. Kochi, "FreeRadicals", J. Wiley, New York, 1973).

The free-radical initiators are generally used in amounts of from about0.01 to about 1% by weight, based on the polyarylene ether sulfones orpolyarylene ether ketones used. It is, of course, also possible to usemixtures of different free-radical initiators.

WO 87/00540, inter alia, has disclosed correspondingly modifiedpolyphenylene ethers, which are preferably mixed with polyamides asblend component.

The novel molding compositions comprise, as component B), from 0.1 to50% by weight, preferably from 1 to 35% by weight and in particular from5 to 25% by weight, of a phosphazene of the general formula I

    (PN.sub.2-x H.sub.1-y).sub.z                               I

where the numerical values of x, y and z, independently of one another,are:

1>x>0.05, preferably 0.8>x>0.15, in particular 0.7>x>0.3

1>y>0.05, preferably 0.7>y>0.05, in particular 0.6>y>0.1

and

z>1

Examples of suitable preparation processes are described in Gmelin'sHandbuch der anorganischen Chemie, 8th edition (1965), Verlag Chemie,Weinheim/Bergstr.; System No. 16 (phosphorus), Part C, p. 302-329.

Phosphazenes I are generally obtainable by reacting a phosphorus halideor a phosphorus nitrogen halide with ammonia, removing firstly ammoniumhalide and then ammonia, while the temperature is raised from therespective starting temperature to a temperature in the range from 500to 850° C., in particular from 550 to 780° C. and very particularly from580 to 780° C.

Suitable phosphorus halides or phosphorus nitrogen halides are those of3- or 5-valent phosphorus, and preference is given to chlorides, such asPCl₃, PCl₅ or (PNCl₂)₃. In the reaction with ammonia, startingtemperatures generally depend, for example, on the particular materialcondition of the halide used, for example room temperature for thereaction of PCl₅ with ammonia: ##STR6##

While ammonium chloride is removed by sublimation, rising temperaturegives formation, formally, of the compounds P(NH₂)₅, PN₃ H₄, PN₂ H andP₃ N₅.

The formulae here are those which may be determined by elementalanalysis (also often termed the abundance of the various elementsrelative to one another).

The elements P, N and H constituting these compounds are probablypresent here in a three-dimensional lattice, as shown below. Mixtures ofoligomeric to polymeric compounds with undefined degree of condensationz are present.

Increasingly crosslinked phosphazene structures of the stoichiometry offormula I are developed with rising temperature and cleavage of ammonia.##STR7##

The phosphazenes I used according to the invention in the moldingcompositions probably have structures intermediate between II and III(continuous transition between the structures), the degree ofcondensation z of which, as given in formula I, is variable andgenerally cannot be quantitatively determined.

It is likely that z may generally be infinite, and can usually take avalue greater than 10²⁵. z is frequently up to 10³⁰, preferably up to10²⁵.

Definition of these compounds is therefore usually restricted to givingtheir elemental make-up (also frequently termed the abundance of thevarious elements relative to one another), which may be determined byelemental analysis.

The novel thermoplastic molding compositions may also comprise, ascomponent C) conventional additives and processing aids. The proportionof these additives is generally not more than 70% by weight, inparticular not more than 50% by weight, based on the total weight ofcomponents A) to C).

Additives which may be mentioned are impact modifiers (also termedelastomeric polymers or elastomers), which may be present in amounts ofup to 20% by weight, preferably up to 15% by weight.

Conventional rubbers are suitable, e.g. ethylene copolymers withreactive groups, acrylate rubber and polymers of conjugated dienes, suchas polybutadiene rubber and polyisoprene rubber. The diene polymers may,in a manner known per se, be partially or completely hydrogenated. Otherexamples of possible rubbers are: hydrogenated styrene butadiene rubber,ethylene-propylene-diene rubber, polybutylene rubbers, polyoctenamerrubbers, ionomers, block copolymers of vinylaromatic monomers withdienes, such as butadiene or isoprene (known per se from EP-A 62 282)with the structure M¹ M² -, M¹ M² M¹ M² - or M¹ M² M¹ -, where theseblock polymers may also comprise segments with random distribution, andalso star-block copolymers. Polymers which have proven particularlysuitable are those of conjugated dienes, such as polybutadiene rubber orpolyisoprene rubber. Synthetic rubbers of this type are familiar to theperson skilled in the art and are reviewed in Ullmanns Encyklopadie derTechnischen Chemie, 4th edition, Vol. 13, pages 595 to 634, VerlagChemie GmbH, Weinheim, 1977.

Other additives which may be mentioned are heat stabilizers and lightstabilizers, lubricants, mold-release agents, colorants, such as dyesand pigments in usual amounts. Further additives are reinforcing agents,such as glass fibers, asbestos fibers, carbon fibers, aromatic polyamidefibers and/or fillers, gypsum fibers, synthetic calcium silicates,kaolin, calcined kaolin, wollastonite, talc and chalk.

Low-molecular-weight polymers are also possible additives, particularpreference being given to polyethylene wax as lubricant.

The desired properties of the end products can be controlled to a largeextent via the type and amount of these additives.

The novel molding compositions may be prepared by processes known perse. In a preferred embodiment, preparation is by adding component B),and also C), to the melt of component A).

It is expedient to use extruders for this purpose, e.g. single-screwextruders or twin-screw extruders, or other conventional plasticatingequipment, such as Brabender mixers or Banbury mixers.

The plastics mixtures may, given the presence of a thermoplasticpolycondensate, then be subjected to another thermal treatment, i.e. asolid-phase post-condensation. The molding composition, in the formappropriate for the particular process, is annealed in annealingassemblies, such as a tumbling mixer or continuously- or batch-operatedconditioning tubes, until the desired viscosity number VN or relativeviscosity ηrel, for example of the polyamide, is achieved. Thetemperature range for the annealing depends on the melting point of thepure component A). Preferred temperature ranges are below the respectivemelting point of A) by from 5 to 50° C., preferably from 20 to 30° C.The process preferably takes place in an inert gas atmosphere, preferredinert gases being nitrogen and superheated steam.

The residence times are generally from 0.5 to 50 hours, preferably from4 to 20 hours. Moldings are then produced from the molding compositionsby means of conventional apparatuses.

The novel molding compositions have good processability, and also goodflame retardancy, in particular no burning drops. They are thereforesuitable for producing fibers, films and moldings of any type, inparticular those used in the electrical sector, and also the electronicsindustry (e.g. casings in the office and IT sectors, coil formers,circuit breakers, multipoint connectors, switch parts, covers andcomputer cases).

EXAMPLES Component A

A1: Poly-ε-caprolactam with a viscosity number VN of 151 ml/g, measuredas 0.5% strength solution in 96% strength by weight H₂ SO₄ at 25° C.;Ultramid® B3 from BASF AG.

A2: Nylon-6,6 with a VN of 148 ml/g, Ultramid® A3 from BASF AG.

A3: Polybutylene terephthalate with a VN of 130 ml/g, measured inphenol/dichlorobenzene (1:1) at 25° C., Ultradur® B4500 from BASF AG.

A4: Poly-2,6-dimethyl-1,4-phenylene ether with an average molecularweight (M_(W)) of 40,000 (GPC in chloroform against a polystyrenestandard at 25° C.).

A5: Impact-modified polystyrene KR 2756 from BASF AG with 9% by weightof polybutadiene. The median particle size of the soft component (d₅₀)was 1.9 μm.

A6: Polycarbonate made from bisphenol Aiphosgene with a VN of 62.4 ml/g,measured in dichloromethane as 0.5 strength by weight solution at 23° C.

A7: An ASA graft polymer built up from a graft base of

A₁₁ : 98% by weight of n-butyl acrylate and

A₁₂ : 2% by weight of tricyclodecenyl acrylate and a graft of

A₂₁ : 75% by weight of styrene

A₂₂ : 25% by weight of acrylonitrile

in a mixture with a hard matrix based on an SAN polymer built up from:

A₃₁ : 80% by weight of styrene and

A₃₂ : 20% by weight of acrylonitrile.

The viscosity number of the hard matrix was 83 ml/g, measured on a 0.5%strength by weight solution in dimethylformamide at 23° C.

Preparation of Component B

To synthesize phosphazenes of the general formula (PN_(2-x)H_(1-y))_(z), 800 g of PCl₅ was placed in a 6 l rotary tubular vesselmade from quartz glass. With rotation at about 1-5 rpm, the PCl₅ wasreacted by introducing a stream of ammonia gas at 48 Nl/h. During this,the temperature was brought to 100° C. within a period of 5 h and heldfor 10 h at that level. The temperature was then increased to 340° C.within a period of 5 h and held for 5 h. The final temperature desiredin each case, which was from 470 to 800° C., was then established usinga heating rate of 20° C./h. This final temperature was held for 5 h.Ammonium chloride produced as by-product during the reaction evaporatedcompletely (T_(sub) =340° C.) and was discharged with the gas stream.After cooling the furnace, the desired phosphazenes could be obtained ascolorless solids.

The make-up of the resultant phosphazenes was determined by elementalanalysis.

B/1 PN₁.39 H₀.46 prepared at a final reaction temperature of 780° C.

B/2 PN₁.97 H₁.00 prepared at a final reaction temperature of 450° C.(for comparison in accordance with EP 417 839)

Component C

C1: Silanized chopped glass fiber with an average diameter of 10 μm

C2: Styrene-butadiene-styrene three-block copolymer (hydrogenated) witha styrene content of 29% by weight (Kraton® G1650 from Shell AG)

Preparation of the Thermoplastic Molding Compositions

Components A) to C), in the proportions given in the table, were blendedin a ZSK 25 at 5 kg/h and 120 rpm, and the extrudate was cooled in awater bath and then pelletized, and also dried at 80° C. for 10 h underreduced pressure. The chopped glass fibers were metered into the meltstream.

The processing temperatures are given in Table 1.

An injection molding machine was used to produce 1/16" test specimensfrom the pellets at 260 and 280° C., respectively (Examples 4, 5 and10). Specimens were tested after the usual conditioning in accordancewith UL94 (flammability test).

The make-ups of the molding compositions and the test results are givenin the table.

                  TABLE                                                           ______________________________________                                                              Processing                                                  temperature UL94  Burning                                                   Example Make-up [% by weight] [° C.] [1/16"]  drops                  ______________________________________                                        1      80 A1 20 B1     260*      V-0   no                                       2 60 A1 15 B1 25 C1 260 V-0 no                                                3* 55 A1 20 B2 25 C1 260 V-2 yes                                              4 85 A2 15 B1 280 V-0 no                                                      5 60 A2 15 B1 25 C1 280 V-2 no                                                6* 60 A2 15 B2 25 C1 280 V-2 yes                                              7 80 A3 20 B1 260 V-0 no                                                      8 55 A3 20 B1 25 C1 260 V-0 no                                                9* 55 A3 20 B2 25 C1 260 n.c. yes                                             10 39.5 A4 45 A5 12 B/1 280 V-0 no                                             3.5 C2                                                                       11 66 A6 22 A7 12 B1 260 V-0 no                                             ______________________________________                                         *for comparison                                                               n.c. = not classified                                                    

We claim:
 1. A flame-retardant thermoplastic molding compositioncomprisingA) from 5 to 99% by weight of a thermoplastic polymer, B) from0.1 to 50% by weight of a phosphazene of the general formula I

    (PN.sub.2-x H.sub.1-y).sub.z                               I

where the numerical values of x, y and z, independently of one another,are as follows:1>x>0.05 1>y>0.05 z>1, and C) from 0 to 70% by weight ofother additives and processing aids, where the total of the percentagesby weight of components A) to C) is 100%, and where component B) isobtained by reacting a phosphorus halide or a phosphorus nitrogen halidewith ammonia, where firstly ammonium halide and then ammonia areremoved, while the temperature is raised from the respective startingtemperature to a temperature in the range of from 500 to 850° C.
 2. Aflame-retardant thermoplastic molding composition as claimed in claim 1,in which the thermoplastic polymer A) is selected from the classconsisting of polyesters, polycarbonates, polyamides, polyolefins,polyoxymethylenes, vinylaromatic polymers, polyarylene ethers andpoly(meth)acrylates and mixtures of these.
 3. A flame-retardantthermoplastic molding composition as claimed in claim 1, where thetemperature is raised from the respective starting temperature to atemperature in the range from 550 to 780° C.
 4. A flame-retardantthermoplastic molding composition as claimed in claim 1, comprisingA1)from 10 to 80% by weight of a polybutylene terephthalate, A2) from 0 to40% by weight of a polyethylene terephthalate, A3) from 1 to 40% byweight of an ASA or ABS polymer or mixtures of these, B) from 1 to 35%by weight of a phosphazene as claimed in claim 1, and C) from 0 to 40%by weight of a fibrous or particulate filler or mixtures of these.
 5. Aflame-retardant thermoplastic molding composition as claimed in claim 1,comprisingA1) from 10 to 80% by weight of a polycarbonate, A2) from 0 to40% by weight of a polyester, A3) from 1 to 40% by weight of an ASA orABS polymer or mixtures of these, B) from 1 to 35% by weight of aphosphazene as claimed in claim 1, and C) from 0 to 40% by weight of afibrous or particulate filler or mixtures of these.
 6. A fiber or filmobtained from the flame-retardant thermoplastic molding composition asclaimed in claim
 1. 7. A molding obtained from the flame-retardantthermoplastic molding composition as claimed in claim
 1. 8. A coilformer, a circuit breaker, a multipoint connector, a switch part, acover or a computer case obtained from the flame retardant thermoplasticmolding composition as claimed in claim 1.